Base film and pressure-sensitive adhesive sheet provided therewith

Abstract

To prevent bumps on the circuit side of a bump-bearing wafer from getting crushed when grinding the back side of said wafer while protecting the circuit side with a surface-protection sheet, and also to minimize the formation of dimples and cracks on the side being ground. [Solution] This base film for a pressure-sensitive adhesive sheet bonded to a semiconductor wafer comprises: (A) a layer obtained by using energy rays to cure a formulation containing a urethane (meth)acrylate oligomer and a thiol-group-containing compound; and (B) a layer comprising a thermoplastic resin.

The invention claimed is: 
     
       1. A pressure sensitive adhesive sheet to be adhered on a semiconductor wafer, comprising:
 a pressure sensitive adhesive layer on a base film, 
 said base film comprising (A) a layer of a cured product in which a composition including a urethane (meth)acrylate oligomer, a thiol group containing compound, and an energy ray curable monomer is cured by an energy ray irradiation before adhering the pressure sensitive adhesive sheet to the semiconductor wafer, and (B) a thermoplastic resin layer, 
 wherein a content of the thiol group containing compound of said composition is 2 to 100 mmol with respect to 100 g of urethane (meth)acrylate oligomer. 
 
     
     
       2. The pressure sensitive adhesive sheet as set forth in  claim 1 , wherein a content of the thiol group containing compound of said composition is 4 to 85 mmol with respect to 100 g of urethane (meth)acrylate oligomer. 
     
     
       3. The pressure sensitive adhesive sheet as set forth in  claim 1 , wherein a compressive stress of the pressure sensitive adhesive sheet at 23° C. is 0.05 to 7 MPa. 
     
     
       4. The pressure sensitive adhesive sheet as set forth in  claim 1 , wherein said layer (A) is formed on the thermoplastic resin layer (B). 
     
     
       5. The pressure sensitive adhesive sheet as set forth in  claim 1 , wherein the thermoplastic resin layer (B) comprises a plurality of layers. 
     
     
       6. The pressure sensitive adhesive sheet as set forth in  claim 1 , wherein the thiol group containing compound is selected from the group consisting of nonyl mercaptan, 1-dodecanthiol, 1,2-ethanedithiol, 1,3-propanedithiol, triazinethiol, triazinedithiol, triazinetrithiol, 1,2,3-propanetrithiol, tetraethyleneglycol-bis(3-mercaptopropionate), trimethylolpropanetris(3-mercaptopropionate), tris[(3-mercaptopropionyloxy)-ethyl]-isocyanurate, 1,4-bis(3-mercaptobutryloxy) butane, pentaerythritol tetrakis(3-mercaptobutylate), and 1,3,5-tris(3-mercaptobutyloxyethyl)-1,3,5-triazine-2,4,6-(1H,3H,5H)-trione. 
     
     
       7. The pressure sensitive adhesive sheet as set forth in  claim 1 , wherein the thermoplastic resin layer (B) comprises a thermoplastic resin selected from the group consisting of polyethyleneterephthalate, polyimide, polyetheretherketone, polyvinylchloride, polyvinylidenechloride, polyamide, polyurethane, an acrylic resin, a fluorine resin, a cellulose resin, and a polycarbonate resin. 
     
     
       8. The pressure sensitive adhesive sheet as set forth in  claim 1 , wherein the thermoplastic resin layer (B) comprises a thermoplastic resin selected from the group consisting of polyimide, polyetheretherketone, polyamide, polyurethane, a fluorine resin, a cellulose resin, and a polycarbonate resin. 
     
     
       9. The pressure sensitive adhesive sheet as set forth in  claim 1 , wherein the energy ray curable monomer comprises a (meth)acrylate having an alicylic structure. 
     
     
       10. The pressure sensitive adhesive sheet as set forth in  claim 1 , wherein the energy ray curable monomer comprises a (meth)acrylate having an aromatic structure. 
     
     
       11. The pressure sensitive adhesive sheet as set forth in  claim 1 , wherein the energy ray curable monomer comprises a (meth)acrylate having a heterocyclic structure.